Seems like JVC projectors leak light all over the place, out of the lens. This is especially true if you are using a lot of vertical lens shift. That's the bad news.
The good news is that while it covers a wide area, it's so dark as to be a non-issue. I remember still being able to spot the faint light on my off-white front wall of my theater when I reviewed the RS2 last year (and more so, with my RS1), but only on very dark scenes, and if looking! With my now dark, rust colored walls, the newer RS20's light leak is completely invisible to my eyes in a completely darkened room.
JVC DLA-RS20 Image Noise
JVC has stuck with higher end Silicon Optix for their image processing. They are using the Silicon Optix Reon-VX. Good stuff! The Reon-VX is found in a number of excellent projectors. I'm not aware of any notable flaws in image processing. Mosquito noise is just visible, in normal amounts, without the Noise Reduction engaged. I don't see a need to implement it, but that is personal taste. Performance on motion artifacts is very good. As you can imagine, the RS20 easily passes all the other related related tests on the HQV test disc, as that widely used test disc is put out by Silicon Optix.
DLA-RS20 Audible Noise
The new JVC RS20 is definitely quieter than my old RS1, and therefore also the RS2. It's still not the quietest projector around, but JVC is now claiming only 19db in low lamp mode (Normal). It is also quieter than the older models in high lamp mode (High). It is now quieter than just about all the DLP projectors, and a bit quieter than the Epson Home and Pro Cinema series projectors (3LCD). On the other hand, it still makes more audible noise than the extremely quiet Panasonic and Mitsubishi home theater projectors.
Of course, none of that matters. What does matter, is whether it is quiet enough for your room and your sensitivity. In Normal mode, no one is going to have an issue. In High mode, a very small group of folks might, but I doubt that it will be a deal breaker for anyone. JVC lowered the audible noise enough (High mode) to take it out of the major concern category for people who have the projector mounted almost directly overhead. If shelf mounted, it should not be an issue, as the shelf itself will absorb some of the sound eminating from the RS20. Let's put it this way - if the RS20 is still too noisy for you, then you will find that there are only a handful of projectors that can do noticeably better in this regard.